Parking devices are necessary for metropolitan areas because there are so many vehicles but limited parking spaces. Parking towers were developed to meet the needs. However, such conventional parking towers generally have complicated structures and high manufacturing cost so that few people are willing to invest their money in manufacturing the parking towers. In other words, the conventional parking lots include a plurality of parking units which have their own driving mechanism and can be operated independently. Accordingly, many motors, cables, sensors etc. are needed. This could make a lot of money if there are enough parking units most of which are used frequently. On the contrary, if the conventional parking device is made in a small scale and is not used for commercial purpose, too many motors, cables, sensors etc. will become a burden to the owner(s).
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional parking device.